Do you mean from clawing at himself to try to free himself ? I have wondered about that quite a lot with hanging. It would seem, compared to other types of suicide, that no matter the intent prior to hanging, once it begins the human body almost cannot help but try to clutch and free itself. I'm just speculating but I have wondered. But in that , I never thought about literal scratches left on the skin from doing so, but it makes sense.
Do we know where Lennon's scratches were? If they were primarily around the face and neck and upper torso, then I might could see that. Otherwise I don't know.
I just saw of this case on FB and I'm very sad. It seems almost certainly it needs to be looked into as a potential ' criminal investigation' at the very least.